SCIENCE OF LIGHT
AND HEALTH

we evolved with natural light

natural light is full spectrum and dynamic

natural light varies with the time of day, time of year, and place on earth

daylight is bright and cool, light from a candle or fire is soft and warm

Figure 1. Natural light is dynamic and full spectrum. Natural light is bright and cool during the day (contains lots of blue light), warm and soft at sunset (contains less blue and more red light), and has no deep blue light at night. A prism can be used to split light into its constituent colors and show how the ratio of blue to red light changes with the time of day. Note also that natural light contains all the colors of the rainbow which is why we look and see our best with natural light!

the human eye has a 3rd photoreceptor which constantly senses the time of day

Figure 2 (a) (above). In 2002 scientists discovered special ganglion cells in our retina which sense the time of day by measuring the amount of deep blue light hitting our eye. During the day deep blue light tells our body to be awake and alert, while at night the absence of deep blue light tells our bodies to rest and recover. (Figure credit: lightingeurope.org)

Figure 2 (b) (right). Rods and cones transmit the visual information to the visual center of the brain via the optic nerve (green path). The ganglion cells are connected with the superior cervical ganglion in the spinal cord and with the suprachaiasmatic nucleus (SCN) by the retinohypothalamatic tract (the blue path). The SCN uses the pineal gland and hormone balance to synchronize the body with the outside world. (Figure credit: lightingeurope.org)

we evolved with dynamic full spectrum light

the cycles of natural light tell us when to be awake and when to rest

Figure 3 (a). Sunlight is bright and cool during the day (contains lots bio-active deep blue light), warm and soft at sunset (contains lots of red light, and less bio-active deep blue light). Light from a candle or a fire contains almost no bio-active deep blue light. Light from Sunlight Inside products is full spectrum and automatically changes throughout the day, closely matching sunlight during the day and then providing candle and fire light at night.

Figure 3 (b). The light spectrum from most artificial light sources is fixed (does not change during the day) and is therefore set to approximate EITHER daylight (cool-white) OR sunset (warm-white). Cool white products contain more bio-active deep blue, while warm-white products contain more red light. Unfortunately even the warm-white (sunset) light sources still contain meaningful amounts of bio-active blue light (as shown in the red boxes) which means they continue to stimulate our bodies when used at night. Incandescent bulbs (original Edison style filament bulbs) offer the least amount of stimulating bio-active blue, but should still be dimmed at night to reduce their blue content further. While incandescent and some halogen sources can be used safely at night, they cannot deliver the bright blue light we need to feel awake and alert during the day. Furthermore incandescent and halogen light sources are very inefficient (only ~5% of incoming energy comes out as light) which is why they are being phased out. As light from a prism shows, fluorescents do not produce full spectrum light which is why they distort the visual appearance of people and objects.

Figure 3 (c) (left).The light emitted by smartphones, monitors and TVs contains a lot of bio-active blue which is one reason why these devices keep you awake at night. To mitigate the impact of blue light from screens at night we recommend using f.lux for PCs and Andriod, and Nightshift for iOS devices! These software solutions shift the balance of screen light from blue to red at night to reduce their stimulating effect. Studies have shown that watching Television generally delivers much less bio-active deep blue to your eye because of the substantially longer viewing distances (and darker images) – but this math is different if you’re a gamer sitting up close!

The light emitted from screens intentionally does not replicate daylight in order to provide the red, green, blue (RGB) control needed to form different images. The partial spectrum of light emitted from screens means that screens are generally a poor source of illumination, light from screens distorts the appearance of people and objects.

circadian rhythms are a cornerstone of our health and wellness

Figure 4. Our circadian cycles regulate our energy levels, performance, metabolism and our recovery. Regular exposure to cycles of natural light are required to synchronize these circadian rhythms. Unfortunately most of us don’t get enough natural light during the day and get too much artificial light at night. Studies show that artificial light at night disrupts our circadian rhythms and thereby increases the risk of insomnia, depression, cancer, diabetes, and cardiovascular disease. (Figure credit wikipedia.org)

FOR MORE INFORMATION

Please see below for more on the link between light and health. If you’d like to dig deeper into the science we recommend checking the research organization websites, reading the references in the linked documents and consulting with a health professional. Unfortunately we don’t have the bandwidth to catalog the thousands of articles on the link between light and health here. However, please do feel free to send us articles, presentations and other resources you think should be included in our high-level summary below!

organizations focused on light and health

We have a Bottled Sunshine lamp in our bedroom. When I am getting ready to go to bed, the warm evening light is so inviting and comforting. And in the morning, I love how energizing the natural morning light is - makes me feel ready to go tackle the day (even before coffee!)

Krista B. in Albany CA

We have been using the lamp extensively for two months and we LOVE it. Our house gets plenty of natural sunlight during the day so mostly we use the lamp at night to set the tone for our infant daughter (and ourselves). The soft, amber glow is beautiful and really helps as a cue for our household to start winding down once the sun sets. It’s basically the only light we use after 9pm to make sure our baby isn’t getting mixed messages during late night or early morning feedings.

Todd J. in Charleston South Carolina

One or two nights each week I have late evening conference calls with China-based coworkers and using bottled sunshine has made all the difference. Instead of feeling ‘wired’, bottled sunshine casts a soft candle-light glow making it easier to relax and fall asleep after my calls end.

Hamlin M. in Minneapolis Minnesota

I have SAD and for a number of years I have used blue light therapy from August when the sky is a different shade of blue to approximately Feb or March when the sky is the right shade of blue. Bottled Sunshine helps with my feeling of depression. Recently I worked in my office for a longer period of time than usual and I noticed how good I felt. I can only speak for myself but I actually feel calmer and less stressful when I am bathed in ‘the light’. Bottled Sunshine is now in my box of tricks to help with my depression.

Margaret I., retiree in Pennsylvania

The Bottled Sunshine lamp is at home in our combination kitchen/family room. It is on an alcove by the windows. I live in a foggy, cool area with mostly cool weather and marine layers in the morning and sometimes all day. Having the warmth of the lamp changes the entire feeling of the kitchen. I learned early on from my mother the power of lighting in a room. I never use overhead lights (at home or at the office). Lighting is the most important stylistic element when it comes to interior design. Any room looks better with high quality lighting. Overhead lighting provides a harsh glare. A lamp like this turn a room into a cozy retreat.

bottled sunshine fan, in Monterey CA

I live in Michigan which has long winter with grey sky on most days. Bottled Sunshine sits at the center of our kitchen island and lets us forget the outside. Its changing light from warm to cool gets my kids active and going out the door in the morning and then the shift from cool to warm calms them down as we finish dinner and get ready for bed. It is really setting the rhythm of our house.